<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }
        html {
            font-size: 30px;
        }
        .one_p {
            font-size: 2rem;
            font-weight: 1000;
            font-family: "宋体";
            font-style: oblique;
            text-indent: 2em;
        }
    </style>
</head>
<body>
    <h1 style="font-style: italic;">这是个标题</h1>
    <p class="one_p">这是个测试</p>
    <div style="width: 110px;">
        <p style="text-align: justify; border: 1px solid black;">
            一二<span style="text-decoration: underline;">三四</span>五六七八九十
        </p>
    </div>
    <div style="width: 200px; height: 200px; background-color: red; font-size: 16px;">
        <div style="width: 50%; height: 50%; background-color: blue;">
            <p style="font-size: 1.5em;  color: white; line-height: 25px;">今天真是个好天气</p>
        </div>
    </div>
    <div style="width: 100vw; height: 10vh; background-color: rgba(0, 0, 0, 0.7);"></div>
    <p style="text-transform: uppercase;">Hello World</p>
    <p style="text-transform: lowercase;">Hello World</p>
</body>
</html>